This invention relates to a cryogenic envelope for a transmission line. In this respect, a preferred embodiment of the invention will be described in connection with a cryogenic envelope for a flexible superconducting power transmission line.
In order to be commercially attractive, superconductive power transmission lines must have low thermal losses and high reliability. Consequently, it is an object of this invention to provide a transmission line having a cryogenic envelope that is both reliable and results in a low heat-leak structure.
Previously contemplated transmission lines for superconductive power cable have been thought of as being somewhat flexible. This, however, has resulted in designs for relatively expensive, high-heat-leak structures which would have required a relatively large number of refrigeration stations along a given length of transmission line. The cryogenic envelope about to be described, however, employs a plurality of rigid relatively low heat-leak sections which are selectively joined together by shorter flexible sections. In this manner, the flexible sections permit modest changes of direction of the line while, at the same time, permitting the remainder of the line to be constructed in a relatively low heat-leak manner.